arXiv subjects

Mianqi Wang

Publications and source records attributed to Mianqi Wang.

10 recordsLinked to original sources

arXiv2026

Twist Operator BOPE and Entanglement Entropy in 2D Interface CFT

We address several aspects of entanglement entropy of 2D interface CFT using the replica method. Unlike the case of boundary CFT, we consider the boundary OPE (BOPE) of the Rényi twist operator and find a boundary twist operator anchored on the interface. This approach gives the $O(1)$ contribution to the entanglement entropy in terms of the BOPE coefficients of the twist operator. We further analyze entanglement entropy of different intervals and compare our findings with previous holographic results.

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arXiv2026

One-point functions in 2D and 4D SUSY Janus

We calculate the one-point functions of the marginal operator $\mathcal{L}'$ dual to the space-varying dilaton in 4D and 2D holographic Janus interfaces, extending results in arXiv:hep-th/0407073. We compare strongly-coupled supergravity and weakly-coupled CFT limits across $\mathcal{N}=0, 1, 2, 4$ holographic Janus interfaces in 4D SYM, and $\mathcal{N}=0, 4$ Janus interfaces for 2D D1-D5 CFT. Exact agreement between these regimes occurs only for the half-BPS interfaces in both 4D and 2D cases, while for other interfaces they agree to first order of the jump parameter. This result reinforces that exact weak/strong coupling matching for interface observables on supersymmetric (SUSY) conformal manifolds is exclusive to maximally SUSY interfaces.

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arXiv2026

Universality of Dissipation across Holographic Interfaces

Motivated by recent results in spin chains we study dissipation and relaxation in a two-dimensional \ak{holographic} interface conformal field theory (ICFT) in which degrees of freedom on one side of the interface are coupled to an external bath, while the other side remains isolated. In the bulk description this setup is realized by gluing a supersymmetric Janus geometry to a BTZ black hole region, with the coupling implemented through a double-trace deformation. We determine the quasinormal modes in the bulk by solving the double-trace matching conditions of the system and bath. Focusing on the fixed AdS$_2$ descendant channel at large frequency, we introduce the dimensionless ratio $c_{UV}$ as a projected measure of interface-induced suppression of dissipation rate. Analytically we find that in this limit, $c_{UV}$ is independent of coupling details to the bath. It is a strong candidate for a universal interface observable characterizing dissipation and relaxation across the interface, in additional to the $c_{\rm relax}$ raised in earlier work for lattice models.

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arXiv2025

Nonrenormalization Theorem for ${\cal N}=(4,4)$ Interface Entropy

We derive a formula for the half-BPS interface entropy between any pair of ${\cal N}=(4,4)$ theories on the same conformal manifold. This generalizes the diastasis formula derived in arXiv:1311.2202 for ${\cal N}=(2,2)$ theories, which is restricted to the conformal submanifolds generated by either chiral or twisted chiral multiples of ${\cal N}=(2,2)$ supersymmetry. To derive the ${\cal N}=(4,4)$ formula, we use the fact that the conformal manifold of ${\cal N}=(4,4)$ theories is symmetric and quaternionic-Kähler and that its isotropy group contains the $SU(2) \otimes SU(2)$ external automorphism of the ${\cal N}=(4,4)$ superconformal algebra. As an application of the formula, we prove a supersymmetric non-renormalization theorem, which explains the observation in arXiv:1005.4433 that the interface entropy for half-BPS Janus solutions in type IIB supergravity on ${\it AdS}_3 \times S^3 \times T^4$ coincides with the corresponding quantity in their free conformal field limits.

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arXiv2024

Transmission Coefficient of Super-Janus Solution

We calculate the transmission coefficient of the super-Janus interface conformal field theory, both at weak and at strong coupling, where latter is described holographically as a domain-wall solution on AdS$_2\times S^2\times M_4\timesΣ$. Surprisingly we find perfect agreement between the free and strong coupling answer, mirroring a similar unexpected equivalence previously found for the entanglement entropy.

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arXiv2024

Universal Bound on Effective Central Charge and Its Saturation

The effective central charge (denoted by $c_{\text{eff}}$) is a measure of entanglement through a conformal interface, while the transmission coefficient (encoded in the coefficient $c_{LR}$ of the two-point function of the energy-momentum tensor across the interface) is a measure of energy transmission through the interface. It has been pointed out that these two are generally different. In this article, we propose the inequalities, $0 \leq c_{LR} \leq c_{\text{eff}} \leq \min (c_L,c_R)$. They have the simple but important implication that the amount of energy transmission can never exceed the amount of information transmission. We verify them using the AdS/CFT correspondence, using the perturbation method, and in examples beyond holography. We also show that these inequalities are sharp by constructing a class of interfaces that saturate them.

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arXiv2023

Universality of Effective Central Charge in Interface CFTs

When an interface connects two CFTs, the entanglement entropy between the two CFTs is determined by a quantity called the effective central charge. The effective central charge does not have a simple form in terms of the central charges of the two CFTs, but intricately depends on the transmissive properties of the interface. In this article, we examine universal properties of the effective central charge. We first clarify how the effective central charge appears when considering general subsystems of the interface CFT. Then using this result and ideas used in the proof of the $c$-theorem, we provide a universal upper bound on the effective central charge. In past studies, the effective central charge was defined only in two dimensions. We propose an analogue of the effective central charge in general dimensions possessing similar universal properties as in two dimensions.

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arXiv2023

Splitting interfaces in 4d $\mathcal N=4$ SYM

We discuss entanglement entropies in 4d interface CFTs based on 4d $\mathcal N=4$ SYM coupled to 3d $\mathcal N=4$ degrees of freedom localized on an interface. Focusing on the entanglement between the two half spaces to either side of the interface, we show that applying the Ryu-Takayanagi prescription in general leads to multiple natural entanglement entropies. We interpret the different entropies as corresponding to different ways of assigning the 3d degrees of freedom localized on the interface to the two half spaces. We contrast these findings with recent discussions of universal relations for entanglement entropies in 2d interface CFTs and formulate generalized relations for 4d interface CFTs which incorporate our results.

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arXiv2023

AdS Higgs mechanism from double trace deformed CFT

Explicit breaking of a global symmetry in a conformal field theory is holographically dual to giving mass to a gauge field living in AdS via the Higgs mechanism. We show that if this breaking is induced via a double trace deformation the Higgs mechanism is induced via a scalar loop diagram. The mass can be calculated analytically in both bulk and field theory and we find perfect agreement. While representing familiar physics, the mechanism is identical to how the graviton picks up a mass in the holographic dual of a conformal field theory coupled to a bath.

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arXiv2023

Universal Behavior of Entanglement Entropies in Interface CFTs from General Holographic Spacetimes

In previous work universal behavior was conjectured for the behavior of the logarithmic terms in the entanglement entropy of intervals in 1+1 dimensional interface conformal field theories (ICFTs). These putative universal terms were exhibited both in free field theories as well as a large class of holographic models. In this work we demonstrate that this same behavior in fact is realized in any holographic ICFT, significantly strengthening the case for the conjecture.

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